The present invention relates to methods and compositions useful in treating subterranean formations. More particularly, the present invention relates to resin compositions comprising filler particulates that may be useful in subterranean operations, such as formation consolidation, zonal isolation, lost circulation treatments, remedial casing repairs, sealing of leaking packers, well abandonment plugs, and associated methods.
Hydrocarbon wells are often located in subterranean formations that contain unconsolidated particulates (e.g., sand, gravel, proppant, fines, etc.) that may migrate out of the subterranean formation into a well bore and/or may be produced with the oil, gas, water, and/or other fluids produced by the well. The presence of such particulates in produced fluids is undesirable in that the particulates may abrade pumping and other producing equipment and/or reduce the production of desired fluids from the well. Moreover, particulates that have migrated into a well bore (e.g., inside the casing and/or perforations in a cased hole), among other things, may clog portions of the well bore, hindering the production of desired fluids from the well. The term “unconsolidated particulates,” and derivatives thereof, is defined herein to include loose particulates and particulates bonded with insufficient bond strength to withstand the forces created by the flow of fluids through the formation, which may cause the particulates to shift or migrate within the formation and/or into voids therein. Unconsolidated particulates may comprise, among other things, sand, gravel, fines and/or proppant particulates in the subterranean formation, for example, proppant particulates placed in the subterranean formation in the course of a fracturing or gravel-packing operation. The terms “unconsolidated subterranean formation,” “unconsolidated portion of a subterranean formation,” and derivatives thereof are defined herein to include any formation that contains unconsolidated particulates, as that term is defined herein. “Unconsolidated subterranean formations” and “unconsolidated portions of a subterranean formation,” as those terms are used herein, include subterranean fractures wherein unconsolidated particulates reside within the open space of the fracture (e.g., forming a proppant pack within the fracture).
One method of controlling unconsolidated particulates in subterranean formations involves placing a filtration bed containing gravel (e.g., a “gravel pack”) near the well bore to present a physical barrier to the transport of unconsolidated particulates with the production of desired fluids. Typically, such “gravel-packing operations” involve the pumping and placement of a quantity of particulate into the unconsolidated subterranean formation in an area adjacent to a well bore. One common type of gravel-packing operation involves placing a screen in the well bore and packing the surrounding annulus between the screen and the well bore with gravel of a specific size designed to prevent the passage of formation sand. The screen is generally a filter assembly used to retain the gravel placed during the gravel-pack operation. A wide range of sizes and screen configurations are available to suit the characteristics of the gravel used. Similarly, a wide range of sizes of gravel is available to suit the characteristics of the unconsolidated particulates in the subterranean formation. To install the gravel pack, the gravel is carried to the formation in the form of a slurry by mixing the gravel with a fluid, which is usually viscosified. Once the gravel is placed in the well bore, the viscosity of the treatment fluid may be reduced, and it is returned to the surface. The resulting structure presents a barrier to migrating particulates from the formation while still permitting fluid flow.
However, the use of such gravel-packing methods may be problematic. For example, gravel packs may be time consuming and expensive to install. Due to the time and expense needed, it is sometimes desirable to place a screen without the gravel. Even in circumstances in which it is practical to place a screen without gravel, however, it is often difficult to determine an appropriate screen size to use as formation sands tend to have a wide distribution of sizes. When small quantities of sand are allowed to flow through a screen, formation erosion becomes a significant concern. As a result, the placement of gravel as well as the screen is often necessary to assure that the formation sands are controlled. Expandable sand screens have been developed and implemented in recent years. As part of the installation, an expandable sand screen may be expanded against the well bore, cased hole, or open hole for sand control purposes without the need for a gravel-packing. However, expandable screens may still exhibit such problems as screen erosion and screen plugging.